Whenever I want to forge a knife, I always want to find the highest-quality steel possible because that will obviously create the strongest knife. For the best outcome without buying steel, some of my best options are Leaf and coil springs, steel cables, saw blades, railroad spikes, steel files, lawnmower or chainsaw blades, and timing chains.
Many of these are easier to locate than you might think, especially in the modern world. To find out why these 7 scraps are the best for knives, my process of testing them, and what I can make with them, keep reading!
Can’t Any Metal Be Reforged?
Technically, yes, most metals can be heated until malleable and altered into another object. However, all metal isn’t good for creating knives. There are a few tests that will be explored later in this post to identify if the metal in question is a good fit, but the general reason comes down to Chemistry.
What Does Chemistry Have to Do With This?
For metal to be made into a sturdy knife, it has to have one thing: Carbon. Carbon steel is what allows a knife to hold the right shape and stay together when being used. Put simply: The higher the carbon composition, the better the knife.
If I were to use just any metal, my knife might break or dull after only a few uses. For the best results and quality, the 7 scraps mentioned above will give me the best chance of a carbon-strong knife.
What Makes This Scrap Better for Knives?
Since I talked about carbon, there are 3 things that a metal needs to be able to do: Hold an edge, be hardened, and be flexible. If it can accomplish all 3 of these things, I’ll be able to forge a knife out of it.
You may be wondering how something can be hard and flexible, but those are at 2 different times in the forging process. The key is to know that the metal can be both, which can be found when I put it through the various tests to weed out the useless scrap.
How Do I Test for Scrap Metal Viability?
There are a number of tests that I can use to not only determine if the metal scrap can be used to make a knife, but also know if it has enough carbon to yield useful results.
1. What Was it Before?
By far the easiest test, knowing what the scrap was before will help me separate the pile significantly. For example, if the scrap was used for cutting or was constantly under pressure it will probably be usable.
Most steel blades or sharp objects can be forged into quality knives assuming that the scrap is big enough to shape or thick enough to expand.
2. Let the Sparks Fly
The spark test can be found all over the Internet, but the short version is that sparks thrown off of the scrap will help me determine what type of metal the scrap is, from cast iron to carbon steel. There’s a spark chart that I use which can help me pinpoint the metal composition.
With this chart, I know that long, mostly straight sparks mean the scrap in question is mild steel as opposed to the short, condensed sparks of white cast iron.
3. What About the Break Test?
If I’ve done the other tests and am still unsure if I can use it to make a knife, the break test usually gives me a pretty good idea. In this case, the break test involves using a forge.
I have to heat the scrap until it no longer conducts electricity and then use water to make the metal as hard as it will possibly be. With the scrap ready, I put it in a vice grip and tighten it down.
The next step is simple: Hit it with a hammer. If the metal breaks or snaps off, that scrap has a high carbon composition and will make a great knife. If it bends and doesn’t break, there probably isn’t enough carbon for me to use.
There are instances where I’ve had scrap bend before breaking, which can mean it will fall in the middle somewhere. These can usually make a knife of fair quality, but I like to use the carbon-rich scrap.
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Where Do I Find Scrap Metal?
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There are a lot of places to look for scrap metal that usually gets some pretty good results. One of my favourite locations to go to is the junkyard because people tend to get rid of all sorts of machinery without a second thought.
As I mentioned in the introduction, there are a lot of tool blades that are high in carbon. People get rid of chainsaws, circular saws, and old files all the time, so I can usually come out of the junk yard with a solid haul.
Another favorite of mine is a mechanic shop or somewhere that works on cars. Leaf springs, coil springs, and timing chains can all be found on a car and most body shops can’t do anything with those parts.
Since they can’t sell them either, I can generally just ask and walk out with a box of goodies that can be molded and forged into a quality blade later.
Where Else Do I Look?
The last main location that I go for carbon steel is a pawn shop. While I can mostly find everything I need in the first two places for free, a pawn shop is a good alternative. It saves me from sifting through the junk in the heat for hours and sometimes the local automotive shop doesn’t have the quality parts that I can use.
When that happens, I know I can hit a pawn shop and find all kinds of thrown out tools and parts ripe for the forge. I will say that, while they’ll do in a pinch, railroad spikes are the least-effective of the 7 scrap metals for making a knife.
They don’t have as much carbon as the rest, so the knife doesn’t always hold an edge, and it’s not as easy to find a spike these days after it was made illegal to walk along the tracks. Still, if you’re low on supplies for forging you can use a railroad spike.
Do I Have to Go to One of Those?
Again, no. There’s a surprising amount of discarded stuff in any given area that will usually have some good metal scrap. If that’s not the case, trash from a medical facility or a construction site can have great steel scrap.
As far as construction sites, though, I avoid the rebar. It might seem like a good metal because it’s strong, but it’s actually really low in carbon and makes low-quality knives.
What’s the Process of Knife Making?
After I have my quality scrap, I can make the knife. I start by marking the steel in the shape that I want to cut it, so in this case I basically draw a knife on the scrap.
I use a grind belt to get the shape correct, which can take a few hours depending on the starting shape of the scrap. Once I’ve got the shape, I put the steel through heat treatment. This makes your knife stronger and is the reason that the knife doesn’t break when used.
By heating up the metal and dipping it in water, or quenching it, the steel melds together. This treatment will reveal any cracks or warps in the steel, which can really be frustrating. The good news is that right after quenching I have a small window to bend out any warps.
There’s unfortunately not a lot I can do about the cracks, but with the steel heat-treated I can attach the handle. A lot of newer forgers tend to make the handle too big or small, but I’ve figured out a pretty universal grip for almost any hand size.
In case it wasn’t obvious with my choice in scrap, I only use the best quality of handle if I don’t just grind the grip into the knife. Either way, I put the handle on and am left with just one last thing to do: Sharpen it.
Obviously, the whole point of a knife is for it to cut or stab something so this is probably the most important step. I prefer to use a sharpening stone, maybe from watching Rambo one too many times, but I can also use the grinding belt from earlier on a lower setting.
No matter the method, I make sure that every knife I forge from scrap is highly capable of performing whatever task you need it for. Once the knife is sharp (7 ways to test your knife sharpness) I polish the steel and, depending on the purpose, char or stain the handle.
What Knives Can I Make From Scrap?
After the entire process of reforging scrap into knives, I reveal the final product to you. As I said earlier, the size and thickness can play a huge role in what kind of knife that particular piece of scrap is turned into.
I’ve made scrap into anything from pocket knives to a serious hunting knife, but a lot of knives end up being used in the kitchen. Filet, skinning, paring, and boning are just a handful of the options I can make with discarded steel.
I’ve even made bread knives and meat cleavers out of scrap, so whatever you need, you can probably find forged out of those 7 best scrap metals!